When manufacturing an electronic device, a plasma processing such as a plasma etching, a plasma CVD or the like is performed with respect to a workpiece. There is known a plasma processing apparatus for implementing such a plasma processing.
Such a plasma processing apparatus includes a processing vessel, a stage for supporting a workpiece within the processing vessel, and a temperature control system for controlling a temperature of the stage. The stage is provided with a temperature adjusting part formed along a circumferential direction of the stage. The temperature control system includes a bypass flow path, a low-temperature flow path and a high-temperature flow path. The bypass flow path is connected to an inlet and an outlet of the temperature adjusting part such that fluid is circulated between the inlet and the outlet. The low-temperature flow path is connected to the bypass flow path such that a low-temperature fluid is supplied from a low-temperature-side temperature adjusting part to the bypass flow path. The high-temperature flow path is connected to the bypass flow path such that a high-temperature fluid is supplied from a high-temperature-side temperature adjusting part to the bypass flow path. Valves whose opening degrees are changed in conjunction with each other are respectively connected to the bypass flow path, the low-temperature flow path and the high-temperature flow path. By controlling the opening degrees of the valves, the temperature control system controls a temperature of the fluid to be supplied to the temperature adjusting part while constantly keeping a flow rate of the fluid.
There is known an apparatus which controls an internal temperature of a reactor to become a target temperature. This apparatus includes a circulation pipe, a hot water supply pipe and a cold water supply pipe. The circulation pipe circulates the water supplied to a cooling jacket of the reactor. The hot water supply pipe circulates hot water therethrough. The cold water supply pipe circulates cold water therethrough. The hot water supply pipe and the cold water supply pipe are connected to a cooling water circulation pipe through a control valve whose opening degree can be adjusted. In this apparatus, a control device calculates a heat exchange amount required in constantly controlling the internal temperature of the reactor and adjusts the opening degree of the control valve, thereby mixing the water existing within the circulation pipe with the hot water existing within the hot water supply pipe or the cold water existing within the cold water circulation pipe at a mixing ratio which can achieve the calculated heat exchange amount. By supplying the mixed water to the reactor at a constant flow rate, the control device controls the internal temperature of the reactor to become the target temperature.
In the aforementioned apparatuses, a heat exchange medium whose temperature is set at a target temperature by mixing heat exchange media having different temperatures is supplied to a temperature control target. Accordingly, the apparatuses require a mechanism for controlling flow rates of a high-temperature heat exchange medium and a low-temperature heat exchange medium to mix the heat exchange media having different temperatures at a desired mixing ratio. As such, the apparatuses suffer from a problem in that the number of parts used to control the temperature of the medium is increased, thereby making a configuration of the temperature control system complicated.